FIELD OF THE INVENTION
The present invention relates to generally a device for automatically retracting and winding a seat belt when released and more particularly an improvement of a seat belt retracting and winding device of the type having a first spring and a second spring which may be operatively combined in such a way that when an occupant fastens a seat belt, they exert a weak seat belt retracting and winding force, but when the occupant releases the seat belt they exert a strong seat belt retracting and winding force.
Already proposed improved seat belt retracting and winding devices are disclosed in the commonly assigned previous patent applications now pending Morita et al Ser. No. 787,534, which is a continuation application of Ser. No. 656,850, filed on Feb. 10, 1976 and now abandoned, and Ser. No. 809,633 filed on June 24, 1977 issued Nov. 21, 1978 as U.S. Pat. No. 4,126,282.
In these patent applications, disclosed in a specific embodiment is a seat belt retracting and winding device of the type comprising a main body, a seat belt winding shaft rotatably mounted on the main body, spring means comprised of a first spring with one end securely fixed to the main body and a second spring with one end operatively connected to the winding shaft and connected to the first spring in series, thereby imparting the seat belt retracting and winding force to the winding shaft, and control means for causing the spring means to change its seat belt retracting and winding force depending upon whether an occupant fastens a seat belt and is restrained by the tension thereof or the occupant releases the seat belt so that the seat belt is being wound.